Radio communication system, base station apparatus, terminal apparatus, and radio communication method in radio communication system

ABSTRACT

A radio communication system including: a first and second base station apparatuses which include one or more of sells or sectors respectively; and a terminal apparatus, wherein the first and second base station apparatuses and the terminal apparatus performs radio communication, the first and second base station apparatuses includes: a process unit which performs a scrambling process to a first and second transmission data respectively by using a common scrambling code when the first and second transmission data differing each of the cells or the sectors are transmitted to the terminal apparatus; and a transmission unit which transmits the scrambling processed first and second transmission data to the terminal apparatus respectively, and the terminal apparatus includes a reception unit which receives the first and the second transmission data and performs descrambling process to the first and the second transmission data by using the common scrambling code.

FIELD OF THE INVENTION

The embodiments discussed herein are related to a radio communicationsystem, a base station apparatus, a terminal apparatus, and a radiocommunication method in a radio communication system.

BACKGROUND ART

In a LTE-A (LTE-Advanced) system, a radio communication by CoMP(Coordinate Multi Point access) is discussed (for example, Non patentDocuments 1, 2 below).

The CoMP is performed, for example, when a terminal is located in aregion where it can communicate with a plurality of base stations (orsectors), by each base station transmitting data differing from theother by MIMO (Multiple Input Multiple Output) to the terminal.

On the other hand, in a radio communication system such as a LTE, thebase station performs a scrambling process to transmission data (forexample, Non-patent Documents 3, 4 below). For example, the base stationadds transmission data b(0), . . . , b(Mbit-1) and scrambling codes c(i)and calculate a remainder (modulo) of “2” to perform scrambling. Thatis, the following formula is satisfied.

{tilde over (b)}(i)=(b(i)+c(i))mod 2  [Expression 1]

Here, the scrambling code c(i) is a GOLD code of the length of “31”, andis obtained by the following generating polynomials.

c(n)=(x ₁(n+N _(C))+x ₂(n+N _(C)))mod 2  [Expression 2]

x ₁(n+31)=(x ₁(n+3)+x ₁(n))mod 2  [Expression 3]

x ₂(n+31)=(x ₂(n+3)+x ₂(n+2)+x ₂(n+1)+x ₂(n))mod 2  [Expression 4]

Here, the following formula also is satisfied.

x ₁(0)=1, x ₁(n)=0, n=1,2, . . . ,30, N _(C)=1600  [Expression 5]

Further, the initial value of the scrambling code c(i) is obtained bythe following formula.

c _(init) =n _(RNTI)·2¹⁴ +└n _(s)/2┘·2⁹ +N _(ID) ^(cell)  [Expression 6]

That is, the initial value of the scrambling code c(i) is a valuedetermined by the followings.

a terminal number:

n _(RNTI) (RNTI: Radio Network Temporary ID)  [Expression 7]

a (physical) cell (or, sector) number:

N _(ID) ^(cell)  [Expression 8]

and, a slot number:

n _(s)  [Expression 9]

The above numbers are used to determine the initial value of thescrambling code c(i).

Further, as one of conventional art of this type, for example, there isdisclosed (for example, Patent Document 1 listed below) a controllingapparatus or the like, which has transmission assigning means whichselects at least two transmission sectors for transmission to a mobilestation according to a reception quality notified from the mobilestation, and performs a transmission assignment to the mobile station,and transmission means which performs a transmission to the mobilestation by using the same scrambling code from the transmission sectorfor identifying the sector.

Also, for example, there is disclosed (for example, Patent Document 2listed below) a base station apparatus or the like, which has specificscramble generating means which generates scrambling codes specific tothe base station, specific orthogonal sequence generating means whichgenerates orthogonal sequences specific to the sector, andmultiplication controlling unit which controls necessity ofmultiplication of the scrambling codes specific to the base station andthe orthogonal sequences specific to the sector according to necessityof software combining for each physical channel.

-   Patent Document 1: Japanese Laid-open Patent Publication No.    2006-311475-   Patent Document 2: Japanese Laid-open Patent Publication No.    2008-92379-   Non patent Document 1: R1-084203-   Non patent Document 2: 3GPP TS 36.210 V8.6.0-   Non patent Document 3: 3GPP TS 36.211 V8.2.0-   Non patent Document 4: R1-081229

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

As described above, the initial value of the scrambling code isdetermined, based on the terminal number, the cell number, and the slotnumber, wherein the terminal numbers differing between the cells are setby the base station, and the cell numbers differ between the cells.Also, there may be a case that the slot numbers differ between thecells. Therefore, when CoMP transmissions are performed from differentcells to a terminal, the initial values of the scrambling codes differbetween the cells. Therefore, base station and the terminal generatedifferent scrambling codes, and, by using them, perform processes forscrambling and descrambling. Hence, processes of each base station andthe terminal become complicated, and, moreover, the electric powerconsumption increases.

Also, in the Patent Documents 1 and 2, such a case is not disclosed thatdifferent data is transmitted from two sectors. The reason for that is,if different data is transmitted from two sectors by using the samescrambling code, as described in Patent Document 1, a mobile stationreceives two signals, which are interfered, and is not able todistinguish data transmitted from the two sectors.

Means for Solving the Problem

According to an aspect of the invention, a radio communication systemincluding: a first and second base station apparatuses which include oneor more of sells or sectors respectively; and a terminal apparatus,wherein the first and second base station apparatuses and the terminalapparatus performs radio communication, the first and second basestation apparatuses includes: a process unit which performs a scramblingprocess to a first and second transmission data respectively by using acommon scrambling code when the first and second transmission datadiffering each of the cells or the sectors are transmitted to theterminal apparatus; and a transmission unit which transmits thescrambling processed first and second transmission data to the terminalapparatus respectively, and the terminal apparatus includes a receptionunit which receives the first and the second transmission data andperforms descrambling process to the first and the second transmissiondata by using the common scrambling code.

Furthermore, according to an another aspect of the invention, a radiocommunication system including: a first and second base stationapparatuses which includes one or more of cells or sectors respectively;and a terminal apparatus, wherein the first and second base stationapparatuses and the terminal apparatus perform radio communication, theterminal apparatus includes: a process unit which performs a scramblingprocess to a first and second transmission data differing each of thecells or the sectors by using a common scrambling code; and atransmission unit which transmits the scrambling processed first andsecond transmission data to the first and the second base stationapparatuses respectively, and the first and second base stationapparatuses includes: a reception unit which receives the first andsecond transmission data and performs descrambling process to the firstand second transmission data by using the common scrambling code.

Effectiveness of the Invention

It is enabled to provide a radio communication system, a base stationapparatus, a terminal apparatus, and a radio communication method in aradio communication system, which reduce processes of the terminalapparatus. Also, it is enabled to provide a radio communication systemor the like which reduces consumption of electric power at a terminalapparatus or a base station apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration example of a radio communicationsystem;

FIG. 2 illustrates a configuration example of a radio communicationsystem in the downlink;

FIG. 3 illustrates a configuration example of a master base stationapparatus;

FIG. 4 illustrates a configuration example of a slave base stationapparatus;

FIG. 5 illustrates a configuration example of a terminal apparatus;

FIG. 6 illustrates a configuration example of a scrambling codegeneration unit;

FIG. 7 is a flow-chart illustrating an operation example;

FIG. 8 is a flow-chart illustrating an operation example;

FIG. 9 illustrates a configuration example of a radio communicationsystem in the uplink;

FIG. 10 illustrates a configuration example of a master base stationapparatus;

FIG. 11 illustrates a configuration example of a slave base stationapparatus;

FIG. 12 illustrates a configuration example of a terminal apparatus;

FIG. 13 is a flow-chart illustrating an operation example;

FIG. 14 is a flow-chart illustrating an operation example;

FIG. 15 illustrates a configuration example of a terminal apparatus;

FIG. 16 illustrates a configuration example of a terminal apparatus; and

FIG. 17 illustrates a configuration example of a base station apparatus.

MODE FOR CARRYING OUT THE INVENTION

The embodiments to carry out the present invention will be explainedhereafter. FIG. 1 illustrates a configuration example of the radiocommunication system 10. The radio communication system 10 includes twobase station apparatuses (eNB: evolved Node_B, “the base station”,hereafter) 100-1, 100-2, and a terminal apparatus (UE: User Equipment,“the terminal” hereafter) 200. The base stations 100-1, 100-2 transmitdifferent data, and the terminal 200 receives it (the downlink). Also,the terminal 200 may transmit different data to the base stations 100-1,100-2 (the uplink). The base stations 100-1, 100-2 and the terminal 200may perform, so called, CoMP communication. Hereafter, explanations willbe made for the case of the downlink (the first embodiment) and the caseof the uplink (the second embodiment). Further, in 3GPP, a “cell” isdefined in the same manner as, so called, a “sector”, and in theembodiments hereafter, unless otherwise mentioned, a “cell” is explainedas equivalent to a “sector”.

The First Embodiment

First, the downlink will be explained. FIG. 2 illustrates aconfiguration example of the radio communication system 10 in thedownlink. Among the base stations 100-1, 100-2, the base station 100-1is a master base station, while the base station 100-2 is a slave basestation. The master base station 100-1 is, for example, a base stationin connection with the terminal 200 before performing CoMP transmission,and the slave base station 100-2 is, for example, a base stationperforming CoMP transmission. The master base station 100-1 transmits acontrol signal to the terminal 200. The terminal 200 receives, accordingto the control signal, the different transmission data (DSCH)transmitted from the master base station 100-1 and the slave basestation 100-2.

<Configuration Example of the Master Base Station>

A configuration example of the master base station 100-1 in the firstembodiment will be explained. FIG. 3 is a drawing for illustrating themaster base station 100-1.

The master base station 100-1 includes an antenna 101, a reception radiounit 102, a demodulation and decoding unit 103, a connection requestsignal extraction unit 104, a radio link control unit 105, a cellinformation signal generation unit 106, a CoMP communication requestsignal extraction unit 107, a CoMP communication execution determinationand control unit (hereafter, “the control unit”) 108, a radio channelquality information extraction unit 109, a scheduler 110, a controlsignal generation unit 111, a scrambling code generation unit 112, atransmission data buffer 113, an encoding and modulation unit 114, and atransmission radio unit 115.

The antenna 101 transmits a radio signal to and/or receives the radiosignal from the terminal 200.

The reception radio unit 102 outputs the radio signal received by theantenna 101 as a reception signal.

The demodulation and decoding unit 103 performs demodulation anddecoding of the reception signal output from the reception radio unit102.

The connection request signal extraction unit 104 extracts a connectionrequest signal from the reception signal after demodulation or the like.The connection request signal is a signal, for example, which is usedwhen the terminal 200 performs a request for a link connection with themaster base station 100-1.

The radio link control unit 105 takes in the connection request signalfrom the connection request signal extraction unit 104, selects, forexample, a cell number and a terminal number from among a plurality ofinternally held cell numbers and terminal numbers, and then outputs theselected cell number and terminal number to the cell information signalgeneration unit 106 and the scrambling code generation unit 112.

The cell information signal generation unit 106 generates a cellinformation from the cell number and the terminal number output from theradio link control unit 105 and a slot number output from the scheduler110. The generated cell information is transmitted as a cell informationsignal to the base station (for example, the slave base station 100-2),which performs CoMP transmission. Also, the cell information signal isoutput to the encoding and modulation unit 114 to be transmitted to theterminal 200.

The CoMP communication request signal extraction unit 107 extracts aCoMP communication request signal from the reception signal output fromthe demodulation and decoding unit 103. The CoMP communication requestsignal is a signal, for example, transmitted from the terminal 200 whenthe terminal 200 will perform CoMP communication.

The control unit 108 determines whether or not to execute CoMPtransmission, and, when determining to perform CoMP transmission,notifies the slave base station 100-2 of CoMP transmission executionnotice. The control unit 108 determines whether or not to execute CoMPtransmission based on, for example, a radio channel quality output fromthe radio channel quality information extraction unit 109 and a radiochannel quality transmitted from the slave base station 100-2. The CoMPtransmission execution notice is also output to the scheduler 110 andthe cell information signal generation unit 106. Details ofdetermination of execution of CoMP transmission will be explained below.

The radio channel quality information extraction unit 109 extracts radiochannel quality information from the reception signal output from thedemodulation and decoding unit 103. The radio channel qualityinformation is information, for example, which is transmitted from theterminal 200.

The scheduler 110 determines (performs a scheduling), based on the radiochannel quality information output from the radio channel qualityinformation extraction unit 109, an encoding rate, a modulation format,or the like executed in downlink communication with the terminal 200.The scheduler 110 outputs the scheduling information related to thedetermined encoding rate or the like to the control signal generationunit 111. Also, the scheduler 110 transmits a frequency to be used andprecoding information, among the scheduling information, as a CoMPcontrol signal to the slave base station 100-2, and outputs the slotnumber to the cell information signal generation unit 106 and thescrambling code generation unit 112. Further, the scheduler 110 controlsthe encoding and modulation unit 114 and the transmission radio unit 115so that an encoding process or the like to the transmission data isperformed according to the determined scheduling information.

The control signal generation unit 111 generates a control signalincluding the scheduling information output from the scheduler 110, andoutputs it to the encoding and modulation unit 114.

The scrambling code generation unit 112 generates the initial value ofthe scrambling code and subsequent scrambling codes one after another,based on the slot number output from the scheduler 110 and the cellnumber and the terminal number output from the radio link control unit105. Details of the scrambling code generation unit 112 will beexplained below.

The transmission data buffer 113 temporary stores the transmission datatransmitted to the terminal 200 from the master base station 100-1.

The encoding and modulation unit 114 scrambles the transmission dataoutput from the transmission data buffer 113 by using the scramblingcode generated by the scrambling code generation unit 112, and encodesand modulates the scrambled transmission data based on the schedulinginformation. The encoding and modulation unit 114 performs encoding orthe like to the cell information output from the cell information signalgeneration unit 106 and to the control signal output from the controlsignal generation unit 111, and may further perform thereto thescrambling process.

The transmission radio unit 115 performs a weighting process of thetransmission data or the like to the transmission data or the likeoutput from the encoding and modulation unit 114, according to theprecoding information generated by the scheduler 110. Also, thetransmission radio unit 115 generates, for example, a pilot signal (or,a known signal). The output from the transmission radio unit 115 istransmitted as the radio signal via the antenna 101 to the terminal 200.

<A Configuration Example of the Slave Base Station>

Next, a configuration example of the slave base station 100-2 inaccordance with the first embodiment will be explained. The slave basestation 100-2 is similarly configured to the master base station 100-1.

The control unit 108 takes in the CoMP communication request signal fromthe CoMP communication request signal extraction unit 107, furtherreceives the CoMP execution notice from the master base station 100-1,and outputs the CoMP execution notice to the scheduler 110.

The scheduler 110 performs scheduling of the downlink based on radiochannel quality information output from the radio channel qualityinformation extraction unit 109. Also, the scheduler 110 receives theCoMP execution notice from the control unit 108, receives the CoMPcontrol signal from the master base station 100-1, and performs ascheduling for the CoMP transmission. The scheduler controls theencoding and modulation unit 114 and the transmission radio unit 115 sothat an encoding process or the like is performed according to thescheduling.

The scrambling code generation unit 112 takes in the cell informationfrom the master base station 100-1, and generates the initial value ofthe scrambling code and subsequent scrambling codes one after anotherbased on the cell information. Details thereof will be explained below.Since the scrambling code generation unit 112 generates the scramblingcode based on the cell information notified from the master base station100-1, the master base station 100-1 and the slave base station 100-2generate same scrambling codes. The generated scrambling codes areoutput to the encoding and modulation unit 114, and the scramblingprocess is performed to the transmission data transmitted from the slavebase station 100-2.

<A Configuration Example of the Terminal>

Next, a configuration example of the terminal 200 will be explained.FIG. 5 illustrates a configuration example of the terminal 200.

The terminal 200 includes an antenna 201, a reception radio unit 202, ademodulation and decoding unit 203, a radio channel quality measurementand calculation unit (hereafter, calculation unit) 204, a radio channelquality information generation unit 205, a cell information extractionunit 206, a scrambling code generation unit 207, a reception controlsignal extraction unit 208, a terminal setting control unit 209, areception power measurement unit 210, a link connection control unit211, a connection request signal generation unit 212, an encoding andmodulation unit 213, a transmission radio unit 214, a CoMP communicationcontrol unit 220, and a CoMP communication request signal generationunit 221.

The antenna 201 transmits the radio signal to and/or receives the radiosignal from the base stations 100-1, 100-2.

The reception radio unit 202 outputs the radio signal received by theantenna 201 as the reception signal.

The demodulation and decoding unit 203 descrambles the reception signalby using the scrambling code generated by the scrambling code generationunit 207, and performs demodulation and decoding to the reception signalaccording to demodulation method or the like set by the terminal settingcontrol unit 209.

The calculation unit 204 measures the radio quality of each radiochannel on the pilot signal or the like transmitted from the master basestation 100-1 or the slave base station 100-2. The calculation unit 204measures the to radio channel quality by, for example, determining SINR(Signal to Interference Noise Ratio) or the like of the pilot signal.

The radio channel quality information generation unit 205 generatesradio channel quality information based on the radio channel qualityoutput from the calculation unit 204. The radio channel qualityinformation includes, for example, CQI (Channel Quality Indicator) orthe like. The generated radio channel quality information is output tothe encoding and modulation unit 213.

The cell information extraction unit 206 extracts the cell informationfrom among the reception signal output from the demodulation anddecoding unit 203. The extracted cell information is output to thescrambling code generation unit 207.

The scrambling code generation unit 207 generates the initial value ofthe scrambling code and the subsequent scrambling codes one afteranother, based on the cell information including the cell number, theterminal number, and the slot number. The scrambling code generationunit 107 outputs the generated scrambling codes to the demodulation anddecoding unit 203.

The reception control signal extraction unit 208 extracts the controlsignal from the reception signal, and outputs it to the terminal settingcontrol unit 209.

The terminal setting control unit 209 controls the reception radio unit202 and the demodulation and decoding unit 203 so that the receptiondata or the like from the base station 1000-1,100-2 are demodulated anddecoded according to the scheduling information included in the controlsignal.

The reception power measurement unit 210 measures, for example, thereception power of the pilot signal from the reception signal, andoutputs the determination result to the link connection control unit 211and the CoMP communication control unit 220.

The link connection control unit 211 determines whether or not toconnect the links with the base stations 100-1, 100-2 based on thereception power. The link connection control unit 211 determines toconnect the link, when, for example, the reception power is equal to ormore than a threshold value, and determines not to connect the link,otherwise. The link connection control unit 211, when determining toconnect the link, outputs a command signal to the connection requestsignal generation unit 212.

The connection request signal generation unit 212 generates, based onthe command signal, the connection request signal, and outputs it to theencoding and modulation unit 213.

When the reception power is, for example, equal to or more than thethreshold value, the CoMP communication control unit 220 outputs ageneration command of the CoMP communication request signal to the CoMPcommunication request signal generation unit 221.

The CoMP communication request signal generation unit 221 generates,based on a command from the CoMP communication control unit 220, theCoMP communication request signal, and outputs it to the encoding andmodulation unit 213.

The encoding and modulation unit 213 performs an encoding and modulatingprocess to the radio channel quality information, the connection requestsignal, the CoMP communication request signal, and the like.

The transmission radio unit 214 performs control or the like oftransmission power to the encoded radio channel quality information andthe like, and outputs it as the radio signal to the antenna 201. Theradio channel quality information and the like is transmitted as theradio signal to the base stations 100-1, 100-2.

<Configuration Examples of the Scrambling Code Generation Units>

Next, configuration examples of the scrambling code generation unit 112of the master base station 100-1 and the slave base station 100-2, andthe scrambling code generation unit 207 of the terminal 200 will beexplained. FIG. 6 illustrates configuration examples of the scramblingcode generation unit 112, 207, which are known GOLD code generators.

The scrambling code generation units 112, 207 include first and secondregisters (or, flip-flops) 112-1, 112-3, and first through third XOR(exclusive logical add) circuits 112-2,112-4, and 112-5.

The scrambling code generation units 112, 207 generate GOLD codes (or, ascrambling codes) of a length of “31”, and output thereof will be thescrambling codes c(n). The polynomials for generating the scramblingcode c(n) are described as the above Number 2 through Number 4.

<Operation Example of the Downlink>

Next, an operation example in accordance with the first embodiment willbe explained. FIG. 7 and FIG. 8 are flow-charts for illustrating anoperation example. Here, the terminal 200 is assumed to be located in aregion where connection is connectable to both of the master basestation 100-1 and the slave base station 100-2.

First, the master base station 100-1 notifies the terminal 200 of thecell information or the like (S10). The cell information notified by themaster base station 100-1 may include, for example, the cell information(the cell number, the terminal, and the slot number) generated by thecell information signal generation unit 106.

Then, the master base station 100-1 transmits the pilot signal (S11).For example, the pilot signal is generated by the transmission radiounit 115 of the master base station 100-1.

Then, based on the received pilot signal or the like, the terminal 200selects the cell to be an object of transmission (S12), and sets up alink with the selected cell (S13). For example, the reception powermeasurement unit 210 of the terminal 200 measures the reception power ofthe pilot signal, and the link connection control unit 211 determinesthe connection of the link, so that the cell (for example, the masterbase station 100-1) is selected. Then, the connection request signalgeneration unit 212 generates the connection request signal andtransmits it to the master base station 100-1, thus setting up the link.The terminal 200 first connects with the master base station 100-1.

Then, the terminal 200 measures the quality of the radio channel (forexample, CQI) with the master base station 100-1 (S14), and transmitsthe radio channel quality information to the master base station 100-1(S15). For example, the calculation unit 204 of the terminal 200measures the radio channel quality based on the pilot signal, and theradio channel quality information generation unit 205 generates theradio channel quality information, so that the information istransmitted to the master base station 100-1.

Then, the master base station 100-1 performs the scheduling based on theradio channel quality information (S16). For example, the scheduler 110of the master base station 100-1 performs the scheduling based on theradio channel quality information extracted by the radio channel qualityinformation extraction unit 109.

Then, the master base station 100-1 performs a transmission signalprocess (S17). For example, the encoding and modulation unit 114 readsout the transmission data stored in the transmission data buffer 113,and performs encoding process or the like according to the encoding ratescheduled by the scheduler 110. Also, to the control signal includingthe scheduling information generated by the control signal generationunit 111, an encoding process or the like is performed by the encodingand modulation unit 114.

Then, the master base station 100-1 transmits the control signal and thetransmission data to the terminal 200 (S18, S19).

The terminal 200 receives the control signal and the transmitted data,and performs a reception signal process (S20). For example, the terminalsetting control unit 209 controls the reception radio unit 202 and thedemodulation and decoding unit 203, so that demodulation and decodingare performed according to the scheduling information included in thereceived control signal.

Then, the terminal 200 receives the cell information and the likenotified from the slave base station 100-2 and the pilot signal (S21,S22). Then, the terminal 200 selects the slave base station 100-2 as aconnecting base station (S23), and sets up a link with the slave basestation 100-2 (S24).

Then, between the terminal 200 and the base stations 100-1, 100-2, theprocess for CoMP transmission is performed. First, the terminal 200receives the pilot signal from each of the master base station 100-1 andthe slave base station 100-2 (S25, S26), and measures the channelquality of the each radio link (S27). For example, by the calculationunit 204 of the terminal 200, each radio channel quality is measured.Further, at this time, for facilitating identifying the pilot signalfrom the master base station 100-1 and the slave base station 100-2, thepilot signal may be generated based on the cell number of the masterbase station 100-1 and the original cell number of the slave basestation 100-2.

Then, the terminal 200 transmits respectively measured radio channelqualities to the slave base station 100-2 and the master base station100-1 (S28, S30). For example, by the radio channel quality informationgeneration unit 205, each radio channel quality information is generatedand transmitted.

The slave base station 100-2 transmits to the master base station 100-1the radio channel quality information transmitted from the terminal 200(S29). For example, the radio channel quality information extractionunit 109 of the slave base station 100-2 transmits to the master basestation 100-1 the extracted radio channel quality between the slave basestation 100-2 and the terminal 200.

Then, the master base station 100-1 determines whether or not the CoMPtransmission is possible (S31). For example, the control unit 108 of themaster base station 100-1 determines that the CoMP communication ispossible when the radio channel quality from the slave base station100-2 and the radio channel quality extracted by the CoMP communicationrequest signal extraction unit 107 are both equal to or more than thethreshold value. The threshold value to be compared with the radiochannel quality from the master base station 100-1 and the thresholdvalue to be compared with the radio channel quality from the slave basestation 100-2 may be the same, or may be different. Further, the controlunit 108 terminates the series of processes when determining that theCoMP transmission is not possible.

Then, the terminal 200 transmits the CoMP transmission execution requestto the slave base station 100-2 and the master base station 100-1 (S32,S33). For example, the CoMP communication control unit 220 of theterminal 200 outputs a command for the execution request, and, from theCoMP communication request signal generation unit 221, the executionrequest signal is transmitted.

The master base station 100-1 determines that CoMP transmission ispossible (S31), receives the CoMP execution request from the terminal200 (S33), and transmits the CoMP execution notices to the slave basestation 100-2 and the terminal 200 (S34, S35). For example, the controlunit 108 of the master base station 100-1 transmits the CoMP executionnotice to the slave base station 100-2. Also, for example, the controlunit 108 outputs to the scheduler 110 the CoMP execution notice, and,from the scheduler 110, the CoMP execution notice is transmitted to theterminal 200 as the control signal.

Then, the master base station 100-1 and the slave base station 100-2perform a process to synchronize with inter-base station (S36). This isfor enabling the transmission data to be synchronized in the CoMPtransmission and transmitted to the terminal 200. For example, thecontrol units 108 of the master base station 100-1 and the slave basestation 100-2 perform transmission and reception of signal each other,and, by phase synchronization, the process for synchronization isperformed.

Then, the master base station 100-1 performs the scheduling for the CoMPtransmission (S37). For example, the scheduler 110 receives the CoMPexecution notice from the control unit 108, and performs the schedulingbased on the radio channel quality or the like (S29, S30). In thegenerated scheduling information, an operation frequency used for CoMPtransmission and the precoding information are included.

Then, the master base station 100-1 transmits the cell information tothe slave base station 100-2 (S38). For example, the cell informationsignal generation unit 106 takes in the cell number and the terminalnumber from the radio link control unit 105, takes in the slot numberoutput from the scheduler 110, generates and transmits the cellinformation including the cell number, the terminal number, and the slotnumber. For example, the cell number and the terminal number aregenerated by the radio link control unit 105 on setting up the link withthe terminal 200 (S13). The cell information signal generation unit to106 may read out the cell number or the like from the radio link controlunit 105, triggered by the CoMP execution notice from the control unit108. As for the slot number, the scheduler 110 may output the number tocell information signal generation unit 106 by the scheduling (S37).Further, the terminal 200 may notify the determined and calculated radiochannel quality with the slave base station 100-2 directly to the masterbase station 100-1.

Then, the master base station 100-1 transfers the transmission data (forexample, the transmission data 2) to the slave base station 100-2 (S39).For example, the scheduler 110 of the master base station 100-1 readsout a part of the transmission data stored in the transmission databuffer 113 (for example, the transmission data 2) and transmits it tothe slave base station 100-2. The transmission data buffer 113 of theslave base station 100-2 stores the transmission data transmitted fromthe master base station 100-1. The transmission data 1 and thetransmission data 2 are, for example, different transmission databetween the cells.

Then, the master base station 100-1 notifies the transmissioncontrolling information to the slave base station 100-2 (S40). Forexample, the scheduler 110 transmits the scheduling informationincluding the precoding information and the like to the slave basestation 100-2 as the transmission controlling information (S37).

Then, the master base station 100-1 and the slave base station 100-2perform transmission signal processes (S41, S42). For example, thescrambling code generation unit 112 of the master base station 100-1generates the scrambling code based on the cell number and the terminalnumber from the radio link control unit 105 and the slot number from thescheduler 110. The encoding and modulation unit 114 performs thescrambling process to the transmission data 1 by using the scramblingcode. Then, the transmission data 1 is encoded according to thescheduling (S37). On the other hand, the scrambling code generation unit112 of the slave base station 100-2 generates the scrambling code byusing the cell information transmitted from the master base station100-1 (S38), and the encoding and modulation unit 114 performs thescrambling process to the transmission data 2. Then, the transmissiondata 2 is encoded based on the transmission controlling informationtransmitted from the master base station 100-1. As such, since themaster base station 100-1 and the slave base station 100-2 generates thescrambling code from the common cell number, terminal number, and slotnumber, same scrambling codes are generated.

Then, the master base station 100-1 transmits the control signal and thetransmission data to the terminal 200 (S43, S44). In the control signal,besides the encoding rate or the like used for the CoMP transmission,the operation frequency and the precoding information may be included,and the cell information generated by the cell information signalgeneration unit 106 may be also included therein.

Then, the slave base station 100-2 transmits different transmission data(for example, the transmission data 2) from the transmission datatransmitted from the master base station 100-1 to the terminal 200(S45). For example, the transmission data 1 and the transmission data 2are weighted according to the precoding information and transmitted.

Then, the terminal 200 performs reception signal processes to thetransmission data transmitted from the master base station 100-1 and theslave base station 100-2 (S46). For example, the terminal settingcontrol unit 209 of the terminal 200 controls the reception radio unit202 and the demodulation and decoding unit 203 according to thescheduling information included in the control signal so as to receiveeach transmitted data from the master base station 100-1 and the slavebase station 100-2 (S43). At this time, the scrambling code generationunit 207 of the terminal 200 generates the scrambling code based on thecell information (S10 or S43). Since the cell information is same tothose used by the master base station 100-1 and the slave base station100-2, the terminal 200 may generate the scrambling code same to thescrambling codes generated by the base stations 100-1, 100-2. Thedemodulation and decoding unit 203 performs the descrambling process tothe transmission data 1 and the transmission data 2 based on thescrambling code.

As such, in the first embodiment, since the master base station 100-1,when performing the CoMP transmission, transmits the cell information tothe slave base station 100-2 (S38), information to generate thescrambling code is shared, and the common scrambling code is generated.Therefore, in comparison with a case that the base stations 100-1, 100-2generate different scrambling codes and perform the scrambling process,this radio communication system 10 may reduce the processes. Also, sincethe processes are reduced, electric power consumption by the terminal200 and the base stations 100-1, 100-2 is reduced.

Also, the master base station 100-1 transmits the precoding informationto the slave base station 100-2 (S40), and the two base stations 100-1,100-2 transmit different data to the terminal 200 based on the precodinginformation. Therefore, even if different data is transmitted to the twobase stations 100-1, 100-2 by using the common scrambling code, theterminal 200 is able to perform the reception process based on theprecoding information included in the control signal (S43, S46), andthus interference of the two different data is avoided.

The Second Embodiment

Next, an example of the uplink will be explained. The second embodimentrelates to an example of the uplink such that data is transmitted fromthe terminal 200 to the base stations 100-1, 100-2.

FIG. 9 illustrates a configuration example of the radio communicationsystem 10 in accordance with the second embodiment. The master basestation 100-1 transmits the control signal to the terminal 200. Theterminal 200 transmits, according to the received control signal, thedifferent transmission data (USCH) to the master base station 100-1 andthe slave base station 100-2.

<A Configuration Example of the Master Base Station>

Next, a configuration example of the master base station 100-1 inaccordance with the second embodiment will be explained. FIG. 10illustrates a configuration example of the master base station 100-1.

The master base station 100-1 further includes a radio channel qualitymeasurement and calculation unit (hereafter, a calculation unit) 121.The calculation unit 121 determines radio channel quality between basestation 100-1 and the terminal 200 based on the pilot signal or the liketransmitted from the terminal 200, and determines the radio channelquality (for example, CQI).

Also, the scheduler 110 of the master base station 100-1, for performingthe scheduling of the uplink, controls demodulation and decoding unit103 and the reception radio unit 102 according to the generatedscheduling information.

Further, the scrambling code generation unit 112, for performing thedescrambling process to the transmission data or the like transmittedfrom the terminal 200, outputs the generated scrambling code to thedemodulation and decoding unit 103.

<A Configuration Example of the Slave Base Station>

Next, a configuration example of the slave base station 100-2 inaccordance with the second embodiment will be explained. FIG. 11illustrates a configuration example of the slave base station 100-2.

The slave base station 100-2 further includes the calculation unit 121,as well.

Also, the scheduler 110 of the slave base station 100-2, for performingthe scheduling of the uplink, controls the demodulation and decodingunit 103 and the reception radio unit 102 according to the schedulinginformation.

Further, the scrambling code generation unit 112, for performing thedescrambling process to the transmission data or the like transmittedfrom the terminal 200, outputs the generated scrambling code to thedemodulation and decoding unit 103.

<A Configuration Example of the Terminal>

Next, a configuration example of the terminal 200 in accordance with thesecond embodiment will be explained. FIG. 12 illustrates a configurationexample of the terminal 200. This terminal 200 has similar configurationto the terminal 200 of the downlink (FIG. 5).

The terminal setting control unit 209 controls the encoding andmodulation unit 213, so that the encoding process or the like isperformed, according to the control signal, to the transmission data orthe like be transmitted to base stations 100-1, 100-2. Also, theterminal setting control unit 209 controls the transmission radio unit214 according to the precoding information included in the controlsignal, so that the different transmission data are weighted andtransmitted to the base stations 100-1, 100-2.

Also, for performing the scrambling process to the transmission data orthe like to be transmitted to the base stations 100-1, 100-2, thescrambling code generation unit 207 outputs the generated scramblingcode to the encoding and modulation unit 213.

<A Configuration Example of the Scrambling Code Generation Unit>

The scrambling code generation units 112, 207 of each of the basestations 100-1, 100-2 and the terminal 200 are similar to those of thefirst embodiment.

<An Operation Example of Uplink>

Next, an operation example in accordance with the second embodiment willbe explained. FIG. 13 and FIG. 14 are flowcharts illustrating theoperation example.

After setting up the link between the master base station 100-1 and theterminal 200 (S10-S13), the terminal 200 transmits the pilot signal tothe master base station 100-1 (S50). For example, the transmission radiounit 214 of the terminal 200 generates and transmits the pilot signal.In the cell information which the master base station 100-1 transmits(S10), the cell information generated by the cell information signalgeneration unit 106 may be included.

Then, the master base station 100-1 measures the radio channel quality(for example, CQI) of the uplink based on the pilot signal (S51). Forexample, by the calculation unit 121 of the master base station 100-1,the determination and the like are performed.

Then, the master base station 100-1 performs the scheduling of theuplink based on the determined radio channel quality (S16). For example,the scheduler 110 performs the scheduling based on the radio channelquality output from the calculation unit 121.

Then, the master base station 100-1 transmits the control signalincluding the scheduling information of the uplink (S18), and theterminal 200 performs a transmission signal process according to thecontrol signal (S52). For example, the control signal generation unit111 of the master base station 100-1 generates the control signalincluding the scheduling information, and transmits it via the encodingand modulation unit 114. Also, the encoding and modulation unit 213 ofthe terminal 200 performs encoding and modulating process to thetransmission data according to the scheduling information included inthe received control signal.

Then, the terminal 200 transmits the transmission data to the masterbase station 100-1 (S53).

Then, the terminal 200 performs the link set up process or the likebetween the terminal 200 and the slave base station 100-2 (S21-S24).Then, between the terminal 200 and the base stations 100-1, 100-2processes for CoMP transmission are performed.

First, the terminal 200 transmits the CoMP transmission executionrequest to each of the base stations 100-1, 100-2 (S32-S33). Forexample, the CoMP communication control unit 220 of the terminal 200commands the CoMP transmission execution request if the reception powerof each radio channel quality is equal to or more than the thresholdvalue. The CoMP communication request signal generation unit 221,according to this command, generates the CoMP communication requestsignal, and transmits it to the base stations 100-1, 100-2.

Then, the terminal 200 transmits the pilot signal to each of the basestations 100-1, 100-2 (S54, S55).

Then, each of the base stations 100-1, 100-2 measures each radio channelquality (S56, S57). For example, by the calculation unit 121 of each ofto the base stations 100-1, 100-2, the radio channel quality ismeasured.

Then, the slave base station 100-2 transmits the measured radio channelquality to the master base station 100-1 (S58). For example, thecalculation unit 121 of the slave base station 100-2 transmits themeasured radio channel quality to the master base station 100-1.

Then, the master base station 100-1 determines the execution of the CoMPtransmission based on the two radio channel qualities (S31). Forexample, if the two radio channel qualities are both equal to or morethan the threshold value, the control unit 108 determines to execute theCoMP transmission. Further, the threshold value to be compared with theradio channel quality determined and calculated by the master basestation 100-1 and the threshold value to be compared with the radiochannel quality determined and calculated by the slave base station 100may be the same, or may be different.

When executing CoMP transmission, the master base station 100-1transmits the CoMP transmission execution notice to the slave basestation 100-2 and the terminal 200 (S34-S35).

Then, the master base station 100-1 performs a synchronizing processwith the slave base station 100-2 (S36), and, after performingscheduling for CoMP transmission (S37), notifies the cell information tothe slave base station 100-2 (S38), in a similar manner to the firstembodiment. The cell information includes the cell number, the terminalnumber, and the slot number.

Then, the master base station 100-1 transmits to the slave base station100-2 (S40) the transmission controlling information including thescheduling information (S37) of the transmission data or the like forthe uplink, and transmits the control signal to the terminal 200 (S43).In the control signal, the cell information generated by the cellinformation signal generation unit 106 may be included. Also, in thetransmission controlling information and the control signal, theoperation frequency and the precoding information are included.

Then, the terminal 200 performs a transmission signal process accordingto the received control signal (S59). For example, the scrambling codegeneration unit 207 generates the scrambling code based on the cellinformation extracted by the cell information extraction unit 206 (S10or S43), and outputs the generated scrambling code to the encoding andmodulation unit 213. The encoding and modulation unit 213 performs, forexample, the scrambling process by using a same (or common) scramblingcode to the transmission data 1 and the transmission data 2 differingbetween the cells. Also, the terminal setting control unit 209 of theterminal 200 controls the encoding and modulation unit 213 so that theencoding process or the like is performed based on the receivedscheduling information. Further, the terminal setting control unit 209controls the transmission radio unit 214 so that the transmission dataweighted according to the precoding information included in the controlsignal is output.

Then, the terminal 200 transmits each different transmission data (forexample, the transmission data 1 and the transmission data 2) to themaster base station 100-1 and to the slave base station 100-2 (S60,S61). For example, the transmission radio unit 214 outputs thetransmission data weighted according to the precoding informationincluded in the control signal.

Then, the master base station 100-1 performs signal reception processesto the transmitted data 2 (S62). For example, the scrambling codegeneration unit 112 of the master base station 100-1 generates thescrambling code based on the slot number determined by the scheduler 110(S37) and the cell number and the terminal number from the radio linkcontrol unit 105. The generated scrambling code is output to thedemodulation and decoding unit 103, and the descrambling process isperformed to the transmitted data 2. After that, the demodulation anddecoding unit 103 performs demodulating and decoding processes or thelike to the transmitted data.

Also, the slave base station 100-2 performs reception signal processesto the transmitted data 1 (S63). For example, the scrambling codegeneration unit 112 of the slave base station 100-2 generates thescrambling code based on the cell information transmitted from themaster base station 100-1 (S38). The generated scrambling code is outputto the demodulation and decoding unit 103, and the descrambling processis performed to the transmitted data 1. For example, the base stations100-1, 100-2 respectively performs the descrambling processes to thetransmitted data 1 and the transmitted data 2 by using the samescrambling codes to the scrambling code which the terminal 200 used inthe scrambling process.

Then, the slave base station 100-2 transfers the transmitted data 1,which is demodulated or the like, to the master base station 100-1(S64). For example, the demodulation and decoding unit 103 of the slavebase station 100-2 transmits the transmitted data 1 to the master basestation 100-1 under a control or the like of the scheduler 110.

As such, in this second embodiment, since the master base station 100-1transmits the cell information to the slave base station 100-2 (S38),the slave base station 100-2 generates the same scrambling code to thatof the master base station 100-1. Also, since the cell information istransmitted from the master base station 100-1 to the terminal 200, theterminal 200 is able to generate the same scrambling code to those ofthe base stations 100-1, 100-2. Therefore, in comparison to the case ofgenerating different scrambling codes, this radio communication system10 is enabled to reduce the processes. Also, by the terminal 200 on thetransmission side and each of base stations 100-1, 100-2 on thereception side not generating the different scrambling codes, theelectric power consumption may be reduced.

Other Embodiments

Next, other embodiments will be explained. In the above describedembodiments, it is explained that the determination of CoMP transmissionis performed by the master base station 100-1 (see S31 or the like ofFIG. 8). For example, however, such the determination may be performedby the terminal 200. For example, the CoMP communication control unit220 of the terminal 200 may make the determination based on thedetermined radio communication quality, according to whether or not thequality is equal to or more than the threshold value (S27 of FIG. 7). Inthis case, since the determined radio communication quality is nottransmitted to the base stations 100-1, 100-2, processes of the tomaster base station 100-1 are further reduced.

Also, in the above described embodiments, it is explained that the CoMPtransmission execution request is performed by the terminal 200. Forexample, however, the master base station 100-1 may perform theexecution request. In the case of the downlink, for example, when themaster base station 100-1 determines to execute the CoMP transmission(S31), the CoMP execution request may be transmitted to the terminal 200and the slave base station 100-2. After that, the master base station100-1 may perform the determination by notifying the executionnotification (S34, S35). Also, as for the uplink, after thedetermination to execute the CoMP transmission (S31), the CoMPtransmission request may be transmitted to the terminal 200 or the like,the CoMP execution notice is notified (S34-S35), and thus thedetermination is performed. A configuration example of the terminal 200in such a case is illustrated in FIG. 15 (the case of the downlink) andin FIG. 16 (the case of the uplink). In comparison to the abovedescribed embodiments, since there are not the CoMP communicationcontrol unit 220 and the CoMP communication request signal generationunit 221, the terminal 200 further reduces the electric powerconsumption.

Further, in the above described embodiments, an example is explained inwhich the transmission data is transmitted from two base stations 100,that is, the master base station 100-1 and the slave base station 100-2.For example, however, a single base station 100 having a plurality ofthe cells (or, the sectors) may transmit the transmission data. FIG. 17illustrates a configuration example of the base station apparatus 100.The base station apparatus 100 includes a master communication unit150-1, a slave communication unit 150-2, and antennas 101-1, 101-2 eachconnected to communication units 150-1, 150-2. The master communicationunit 150-1 includes the units 102 and the like within the master basestation 100-1, and the slave communication unit 150-2 includes the units102 and the like within the slave base station 100-2. For example, theslave communication unit 150-2 outputs the radio channel qualityinformation to the master communication unit to 150-1, and the mastercommunication unit 150-1 outputs the cell information or the like to theslave communication unit 150-2. Thereby, the base station 100 performsin the downlink and the uplink in a similar manner to the first and thesecond embodiments.

Further, in the above described embodiments, the cell number used forCoMP transmission, the terminal number, and the slot number arerespectively replaced with a CoMP specific cell number, terminal number,and slot number. For example, when the control unit 108 of the masterbase station 100-1 determines the execution of the CoMP transmission(S31), the notice thereof is output to the cell information signalgeneration unit 106. The cell information signal generation unit 106 mayrewrite, according to the notice, the cell number, the terminal number,and the slot number with the CoMP specific numbers. Also, since the cellinformation signal generation unit 106 transmits these to the slave basestation 100-2 as the cell information, the slave base station 100-2generates the same scrambling code to that of the master base station100-1.

Further, in the above embodiments, an example is explained such thatCoMP transmission is performed between the two base stations 100-1,100-2, and the terminal 200. For example, however, the CoMP transmissionmay be performed between more than three base stations 100 and theterminal 200. In this case, any one of more than three base stationbeing the master base station, and the other base station being theslave base station, the cell information is transmitted from the masterbase station to the plurality of the slave base station, in a similarmanner to the above described embodiments.

EXPLANATION OF REFERENCE NUMERALS

-   -   10: radio communication system    -   100: base station apparatus (base station)    -   100-1: master base station    -   100-2: slave base station    -   103: demodulation and decoding unit    -   105: radio link control unit    -   106: cell information signal generation unit    -   107: Comp communication request signal extraction unit    -   108: Comp communication execution determination and control unit        (control unit)    -   109: radio channel quality information extraction unit    -   110: scheduler    -   111: control signal generation unit    -   112: scrabling code generation unit    -   114: encoding and modulation unit    -   150-1: master communication unit    -   150-2: slace communication unit    -   200: terminal apparatus (terminal)    -   203: demodulation and decoding unit    -   204: radio channel quality measurement and calculation unit    -   205: radio channel quality information generation unit    -   206: cell information extraction unit    -   207: scrabling code generation unit    -   208: reception control signal extraction unit    -   209: terminal setting control unit    -   210: reception power measurement unit    -   213: encoding and modulation unit    -   220: Comp communication control unit    -   221: Comp communication request signal generation unit

What is claimed is:
 1. A radio communication system comprising: a firsttransmitter and one or more second transmitters which include one ormore of cells or sectors respectively; and a receiver configured toperform radio communication with the first transmitter and the one orthe more second transmitters, wherein the first transmitter includes: acontrol information generation unit configured to transmit to the one ormore second transmitters information to generate a common scramblingcode by the first transmitter and the one or more second transmitters,the first transmitter and the one or more second transmitters include: aprocess unit configured to perform a scrambling process to transmissiondata by using the common scrambling code respectively, when thetransmission data in each of the cells or the sectors is transmitted tothe receiver respectively; and a transmission unit configured totransmit the scrambling processed transmission data to the receiverrespectively, and the receiver includes a reception unit configured toreceive the transmission data and perform descrambling process to thetransmission data by using the common scrambling code.
 2. A transmitterincluding one or more of cells or sectors for performing radiocommunication with a receiver, the transmitter comprising: a controlinformation generation unit configured to transmit to an othertransmitter information to generate a common scrambling code; a processunit configured to perform a scrambling process to transmission data byusing the common scrambling code, when the transmission data in each ofthe cells or the sectors is transmitted to the receiver; and atransmission unit configured to transmit the scrambling processedtransmission data to the receiver.
 3. A receiver for performing radiocommunication with a first transmitter and one or more secondtransmitters including one or more cells or sectors, the receivercomprising: a reception unit configured to receive scrambling processedtransmission data from the first transmitter and the one or more secondtransmitters, and performs descrambling process to the scramblingprocessed transmission data by using a common scrambling code, whereininformation to generate the common scrambling code is transmitted fromthe first transmitter to the one or more second transmitters, and thescrambling processed transmission data is generated by the firsttransmitter and the one or more second transmitters.
 4. A radiocommunication method in a radio communication system for performingradio communication between a receiver and a first transmitter or one ormore second transmitters including one or more of cells or sectors, themethod comprising: transmitting to the one or more second transmittersinformation to generate a common scrambling code by the firsttransmitter and the one or more second transmitters, by the firsttransmitter, performing a scrambling process to transmission data byusing the common scrambling code respectively, when the transmissiondata in each of the cells or the sectors is transmitted to the receiverrespectively, by the first transmitter and the one or more secondtransmitters; transmitting the scrambling processed transmission data tothe receiver respectively, by the first transmitter and the one or moresecond transmitters; and receiving the transmission data and performingdescrambling process to the transmission data by using the commonscrambling code, by the receiver.
 5. A radio communication method in atransmitter including one or more of cells or sectors, for performingradio communication with a receiver, the method comprising: transmittingto an other transmitter information to generate a common scramblingcode, by a control information generation unit; performing a scramblingprocess to transmission data by using the common scrambling code, whenthe transmission data in each of the cells or the sectors is transmittedto the receiver, by a process unit; and transmitting the scramblingprocessed transmission data to the receiver, by a transmission unit. 6.A radio communication method in a receiver for performing radiocommunication with a first transmitter and one or more secondtransmitters including one or more cells or sectors, the methodcomprising: receiving scrambling processed transmission data from thefirst transmitter and the one or more second transmitters, andperforming descrambling process to the scrambling processed transmissiondata by using a common scrambling code, by a reception unit, whereininformation to generate the common scrambling code is transmitted fromthe first transmitter to the one or more second transmitters, and thescrambling processed transmission data is generated by the firsttransmitter and the one or more second transmitters.